Mode space approach for tight-binding transport simulation in graphene nanoribbon FETs

A mode space tight-binding approach for the simulation of armchair graphene nanoribbon FETs is discussed. It makes use of slab-dependent modes and a novel criterion for mode selection going beyond the one based on the lowest energy subbands. For ideal ribbons we show that, by splitting the modes into decoupled groups, the new method provides results almost identical to the real space with a speedup of more than one order of magnitude. Even in the presence of edge roughness, which tends to couple the modes, the mode space approach still offers a sizable computational advantage with respect to the real space, while retaining a good accuracy.